Circuit breaker



2 Sheets-Sheet 1 Jan. 2, 1951 J G JACKSON ETH.

CIRCUIT BREAKER yFiled May 11, 1948 J. G. JACKSON Erm. 2,536,812

CIRCUIT BREAKER 2 Sheets-Sheet 2 1 VENTOR s.

Jgzc/zsarz QZLV /Zlz'zgann Wg? v /sfffo/m/v/ Jan. 2, 1951 Filed May 11, 1948 Patented Jan. 2, 1951 CIRCUIT BREAKER John G. Jackson and Ralph H. Kingdon, Detroit, Mich., assignors to Square D Company, Detroit, Mich., a corporation of Michigan v Application May 11, 1948, Serial No. 26,448

1I) Claims.

' This invention relates to circuit breakers and more particularly to the current responsive automatic tripping mechanism for automatic electric circuit breakers.

An object of the invention is the :provision oi -an automatic tripping mechanism for an electric f'circuit breaker of combined thermal and magnetic type and of economical and reliable construction for both thermal and magnetic re sponses -f Another object of the invention is the provision of automatic tripping means for an electric circuit breaker employing both thermally and magnetically responsive elements in which the magnetically responsive elements are bodily movable by the thermal to effect tripping on sustained overloads and in which the magnetic elements are independently movable with a substantially prying action to increase the unlatching force in the magnetic response for heavy short circuit currents.

Another object of the invention is the provision of an automatic tripping means for an electric circuit breaker in accordance with the preceding object in which there is provided a common cross bar for a plurality of poles with thermal and magnetic elements individual to the poles cooperating therewith to effect an unlatching movement of the common cross bar and in which cooperating magnetic elements are carried by the common cross bar with one magnetic element engaging an abutment in its movement to eiect a prying or force multiplying movement of the interengaging ends of the cooperating elements. y

Other objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

Figure 1 is a plan View of the circuit breaker according to the present invention, with the cover removed.

Figure 2 is a longitudinal sectional view on the line II-II of Figure 1.

The circuit breaker mechanism with which the automatic tripping means of this invention is specifically shown conforms in general to that disclosed and claimed in the patent to Jackson et al. 2,426,880 granted September 2, 1947, for Cir' cuit Breaker, and the mechanism forms no specie part of the present invention as the automatic tripping means will obviously function with any form of releasable circuit breaker mechanism. The breaker is sealably enclosed within com- 2 gx; plementary cup-shaped base and cover members VI and 2 of insulating material. The circuit breaker is speccally illustrated in three-pole form with the lower end of the base carrying three terminal connectors 3 suitably mounted in vslots within the base and carrying at their internal endstationary contacts 4. Cooperating with the stationary contacts 4 are movable contacts 5, 6 and 'I mounted at the ends of contact blades 8, 9 and Il. The blades S and II are suitably pivoted in the base at I2 and I3 and have a resilient connection by means of springs I4 and I5 to a common insulating Contact cross bar I6. The upper ends of the blades B and II are connected by flexible leads Il and I8 to the movable ends of bimetallic elements I9 and 2l mounted on the forward ends of conducting connectors 22 and 23.

The contact blade 9 has its upper end formed of two arms 24 and 25 pivotally mounted on a pin 255 disposed in opposite side walls of a metallic supporting frame 2l supported in the base by means of a stud 28. Also pivotally mounted on the pin 2E is an operating member 29 of U-shape having its `opposite sides provided with cutout portions indicated at 3| and engaged by hubs 32 on a manually operable handle 33 pivoting about 34 within suitable grooves in the base I and cover 2. To the free end of the operating member 29 are pivoted a pair of lever arms 35 by means of pins 36 with the ends of lever arms 35 connected by a pin 3l extending through slots 38 inthe arm 24 and 25 of the contact blade 9.

Pivoted to the frame 21 by means of a pin 39 is a releasable member 4I normally engaging a latching surface on a common cross bar 42 extending across the three poles of the breaker and pivoted by means of hubs 43 in grooves in the opposite side walls of the base I, being maintained therein by engagement with the back portion of the cover 2. The releasable member 4I is formed to provide a hook portion 44 between which and the pin 3l are disposed a pair of tension springs indicated generally at 45 and being shown more particularly in Figure 2 at the cutaway portion of the arm 24 of the blade 9. The flexible lead 46 interconnects the upper end of the arm 24 with the free end of the bimetallic element. 41 mounted upon the forward end of a terminal connector 48 supported in slots in the base I and cover 2.

' The central portion of the common cross bar 42 is provided with a resilient spring strip 49 forming asmooth latching surface at its back end for the latching end of the releasable member 4I and extending at its forward end to provide a biasing portion 5| engaged with a stationary part 52 on the frame 21 so as to bias the cross bar 42 into latching position. Upon the upper side of the cross bar 42 are mounted a plurality of magnetic yokes 53, one for each pole of the breaker, and having side portions substantially embracing the bimetallic members |9, 2| and 41. These magnetic yokes haveiforward extensions terminating at 54 serving to counterweight the cross bar 42 about its rotative axis. The back ends 0f the yokes 53 terminate in hook portions 55 within which are received complementary groove por tions of armature membersv withthe lower retaining ears shown at 51. Spring sheets 58. mounted on the armature members 56 vretain them in engagement with therportions 55 of the yokes 53 and bias the armatures '56"away-from the yokes into the position shown in Figure Zand against insulating sheets 59 disposed against the connectors22 ,r23 and 48 to insulate the armatures 5,6'therefrom. The armature members 56 are provided with pressed outvportions 6| adapted to engage the bimetallic members I9, 2|.and 41 in the magnetic tripping operation of the. breaker `to exertv a substantially pryingy action to providea force multplying movement for .the magnetic untripping.-

`Adjusting screws 62 threadedyin bridging elements 63,- carriedby the cover Zengage the forward endsof the connectors 22, 23 and 48 to effect the` thermal calibration of the breaker by. locating the position of thefree end of the bimetal through bending ofthe forward end of the connector.

The mechanicaloperation of the circuit breaker mechanism on both manualv and automatic is in general substantially the same as that described in more detail in the previously mentioned Vpatent to Jackson et al. 2,426,880. Y flrieiiy, the parts as shown in Figure 2 are in the on or circuit madeposition. If. the handle 33 isfrotated.counterclockwise, it will rotatethe operating member 29- in-"a clockwise direction to inoye the pin'36 toward the back of base and whenthe pin 3'6 passes through the line joining thegpins 26 and 31 the 'line of force will pass throughcenter and will move the. arms24 and 25' andblade 9 in a counterclockwise direction as viewedin Figure 2 to move the'y movable contact 6 toward cover 2 rto separate the contactsand open the! circuit through the breaker. VWith the con-` tactsopen a reverse or clockwisefmovem'entof the handle 33 will effect areverse movement-through center to again movethe arms 24 and 25 and blade 9;,"into contactsl engaged position. As blade 9 moves the contact cross bar`l6, to whichV it is attached` bymeans of stud I0, will also move and carrythe outer contactv blades 8 and Il therewith .to separate and engage'the contacts 5 and 1 with their respective stationary contacts 4.

"Upon automatic tripping, either thermal or magnetic, as will. be more'. fully explainedhereinalfiler, the bridging crossbar`42 will be rotated in ai 'clockwise direction as viewed in 'Figure 2 by any one or all of the thermal andmagnetic elements of', the plurality of breaker poles into a position whereit unlatches the end ofthereleasable member 4|. When unlatched', the releasable .member {Lmoves in aclockwisedirection under the action of` springs 45 to place the line of force over center with respect to the operating elements of the breaker and eiect the movement of the blade 9, the'bar |6and associated blades `8 and Il. into theirv diysengaged position. In effecting both manual and automatic movements, thev pin 31 4 slides within the slot 38 of the arms 24 and 25. The breaker is reset by moving the handle to the "off position whereupon the releasable member fil is again placed in relatching position in back of the cross bar 42.

With respect to the automatic tripping of the circuit breaker for straight thermal trip upon sustained moderate overloads, oneor more of the bimetallic elements i9, 2| and 41'ex upwardly at their free ends and, by their engagement with the back edges of the armature member or members 59, directly rotate the cross bar 42 about its hubs 43.

Upon the-occurrence of heavy overload or short circuit currentsone or more of the armatures 56 will be attractedtoyokes 53 by the magnetic flux caused by the single turn loops of the bimetals through the'yokes. As an armature 56 moves toward its yoke 53, the pressed out portion 6| will engage the upper side of the respective bimetallic element as an abutment and thereafter thearmature 56 substantially rotates about the engagement of thev pressed out portion 6| withthe bimetal to exert a prying and f orce multiplying action upon the engagement of the armaturel 56 with the yoke at the ears. 51 and hook portion 55. This prying or force multiplying movementalso rotates the cross bar 42 about its-hubs 43 to elect unlatching of the releasable member 4|.

Upon overloads of certain values, it will,l of course, be understood that the releasing motion of the cross bar 42 maybea combined-effect rof the thermal and magneticactions.

One of the principal features of theinvention lies in the provision of` a sensitive, reliable and eiective magnetic tripping by theprying or force 'multiplying movement which results from the en,-

gagement of the pressed o utportion `6| ofthe armature 56 with an abutment, specically illustrated as the blmetallic element 41.so that the required force for the automatic tripping of the circuit breaker magnetically may be brought about with relatively smallandlight elements-of the armature and yoke andwith the single turn provided by the looping of thebimetallic element with the yoke. y Y i .Another important featureof the invention re`-v sides in the'mounting of both of the` cooperating magnetic elements upon the cross-bar andthe, association of the bimetallic elements with the magnetic elements so thatjthe location ofthe cross bar latchk andl its .latching overlap, with, the, releasable memberv 4| is determined in the thermal calibration by movementA of the crossA bar latch through engagement by the bimetallic elements with the magnetic elements.l This farrangernent'of parts particularly contributesto the reliability and uniformity of. the automatic tripping and renders theconstruction lesssusl' ceptible to variation dueto manufacturing .tol-` erances. Y

While certain preferred embodiments of the invention have beenV specifically disclosed, itflis understood that. kthe invention is not'v limited' thereto, as many variations `rwill fb'e readilyap--- parent to those skilled in .the artand the invention is to be given its broadest vpossibleinterprefV tation within the termsofA thefollowing'claims.

What is claimed-isz;

- 1'. In an automatic electric circuit breaker having separablecontacts andmeans releasablel to. eliect automatic separation of saidv contacts, cur rent responsive. latching meansfOr. said releasable, means comprising aflatching surface engaging'lv f Said telecable 'tirati1.110'-V @anbei '5 heated in response to ow of current through the breaker and connected to move said latching surface to unlatching position upon the occurrence of a sustained, moderate current overload, a magnetic yoke connected to said latching surface, a magnetic armature pivoted on said magnetic yoke, the magnetic circuit being energized in ac- -cordance with the current flowing through the `effect automatic separation of said contacts,

current responsive latching means for said releasable means comprising a latching surface engaging said releasable means, a bimetallic member heated in response to flow of current through the breaker and connected to move said latching surface to unlatching position upon the occurrence of a sustained, moderate current overload, a magnetic yoke connected to said latching surface, a magnetic armature pivoted on said magnetic yoke, the magnetic circuit being energized l; in accordance with the current flowing through the breaker, and an abutment engageable by the armature as it is attracted toward the yoke so as to eiect movement of the yoke thereafter from the pivotal mounting of the armature thereon, the yoke movement occurring With a substantially prying action about the armatureabutment engagement to effect movement of the latching surface to unlatching position.

3. In an automatic electric circuit breaker having separable contacts and means releasable to effect automatic separation of said contacts, current responsive latching means for said releasable means comprising a latching surface engaging said releasable means, a bimetallic mem- .ber heated in response to new of current through the breaker and connected to move said latching surface to unlatching position upon the occurrence of a sustained, moderate current overload, a magnetic yoke connected to said latching surface, a magnetic armature pivoted on said magnetic yoke, the magnetic circuit being energized in accordance with the current flowing through the breaker, said bimetallic member being disposed in the path of movement of the armature as it is attracted toward the yoke so that the armature engages the bimetallic memberl as an abutment to effect movement of the yoke thereafter from the pivotal mounting of the armature thereon, the yoke movement occurring with a substantially prying action about the armature-bimetallic member engagement.

4. In an automatic electric circuit breaker having separable contacts and means releasable to effect automatic separation of said contacts, current responsive latching means for said releasable means having a latching surface engaging said releasable means, a bimetallic member heated 1n response to the flow of current through the breaker, a magnetic yoke connected to said latching surface, a magnetic armature pivoted on said magnetic yoke, the magnetic circuit being energized in accordance with the current ilowing through the breaker, said bimetallic member being mounted to move said magnetic yoke and armature bodily upon flexing of the bimetallic member through heating upon the occurrence of a. sustained moderate current overload and moving the latching surface with the yoke to disengage the releasable means, the armature engaging said bimetallic member in its magnetically attracted movement toward the yoke so as to eiect movement of the yoke thereafter from the pivotal mounting of the armature thereon, the yoke movement occurring with a substantially prying action about the armature-bimetallic member engagement to effect movement of the latching surface to unlatching position.

5. In an automatic electric circuit breaker having separable contacts and means releasable to effect automatic separation of said contacts, current responsive latching means for said releasable means having a latching surface engaging said releasable means, a bimetallicmember connected in series circuit With the contacts so as to be traversed by the current passing through the breaker, a magnetic yoke connected to said latching surface and embracing the bimetallic member so as to be energized by the current flowing through the bimetallic member, a magnetic armature pivoted on said magnetic yoke, said bimetallic member flexing on being heated by a sustained moderate current overload to move the yoke and armature bodily to move the latching surface to unlatching position, said armature engaging said bimetallic member as an abutment in its magnetically attracted movement toward the yoke upon the occurrence of heavy overload and short circuit currents so as to eifect movement of the yoke thereafter from the pivotal mounting of the armature thereon, the yoke movement occurring with .a substantially prying action about the armaturebimetallic member engagement in the magnetic tripping operation.

6. In an automatic electric circuit breaker having separable contacts and means releasable to effect automatic separation of said contacts, current responsive latching means for said releasable means comprising a pivotally mounted latching member having a latching surface engaging said releasable means, a bimetallic member heated in response to the flow of current through the breaker and connected to rotate said latching member to move the latching surface to unlatching position upon the occurrence of a sustained moderate current overload, a magnetic yoke supported on said latching member for rotation therewith, a magnetic armature pivoted on said magnetic yoke, the magnetic circuit being energized in accordance'wlth the current flowing through the breaker, and an abutment engageable by the armature as it is magnetically attracted toward the yoke upon the occurrence of heavy overload and short circuit currents so as to effect rotation of the yoke and latching member thereafter from the pivotal mounting of the armature on the yoke, the yoke rotation occurring with a substantially prying action about the armature-abutment engagement to effect rotation of the latching surface on the latching member into unlatching position.

7. In an automatic electric circuit breaker having separable contacts and means releasable to effect automatic separation of said contacts, current responsive latching means for said releasable means comprising a pivotally mounted latching member having a latching surface engaging said relasable means, a bimetallic member heated in response to the flow of current through the breaker and connected to rotate said latching member to move the latching surface to unlatching position upon the occurrence of a sustained moderate current overload, a magnetic yoke supported on said latching member for rotation. therewith.. a magnetic: armature pivoted on said magnetic Iyoke, the magnetic circuit-be.- ng eruiugizedV in` accordance1 with the current ilovvingv through. the breakerL said bimetallic member being. positionedtov .be engaged. by the armature in its magnetically .attracted move ment'. toward the yoke upon the occurrence. of heavy overload andishort circuit4 currents. so` as to-eiect rotation of the yoke Vand iatchingmember thereafter-from the pivotal mounting or". the armature on the yoke and the; rotation of the armature. about its engagement .with the bi metallic member.

8;. Ina .multipolel automatic electric. circuit breaker: having separable contacts in each of the breaker poles and means releasable to. eiect auto.- maticnseparation oi-said contacts, current. responsive latcliing .means for said: releasable means comprisinga pivotally` mounted latching member common to. al1 the breaker polesandA having a latching surface thereon engaging said releasable means,` a plurality ofVv bimetallic. members each heated individually in accordance withv the ow: of currentA through. one of the breaker poles and each connected to rotate the latching mem-- ber and latching surface into unlatching position upon the occurrence of' a sustained, moderate current overload to its respective pole, a plurality of magnetic. yokes mounteduponnsaid common latchingV member and: each energized in accordance with the current ow through one of the breaker poles, a magnetic armature, pivoted on each of the magnetic yokesv andan abutment engageable by each of the armatures in its magnetically attracted movement toward' its associated yoke so as to effect. rotation .of the associated vyoke and. of the common latching member as the attracted armature rotates about itsl engagement with the abutment.

`9; In a multipole. automatic electric circuit breaker having separable contacts in each of the breaker poles and means releasable to effect automatick separation of said contacts, current responsive latching means. forr said releasable -means comprising a pivotally mounted' latching member common. to all the breaker poles and l having azlatohing surface thereon engaging said releasable means, a plurality: of'bimetallic mem bers v'each heated individually in accordance `with the flowV of current through one of. the breaker poles and each connected to rotate the; latching member and latching surface into unlatching position upon the occurrence of a. sustained, moderate current overload to its respective pole,

a. pluralityof magnetic yokes mounted.v upon said 8 .common latching member andV each energized-in accordance with the current dow through one-.of the breaker poles, a magnetic armature pivoted on each of thev magnetic yokes, each oisad bi- .metallic elements being associatedv with one of the magnetic armatures so as, to be engaged thereby as an abutment as the associated armature is magnetically attracted toward the yoke upon the. occurrence of heavy overload. andV short circuit. currents., the yoke associated with the attracted armaturev and thelatching member) bef ing. rotatedinto unlatching position as. the at'- tracted armature rotates about itsV engagement with. its associated bimetallicA member.. 10. In a multipole automatic electric circuit breaker having separable contacts in each. of

the breaker' polesr and means releasable to ef? fect` automatic separation of said' contacts, current responsive latching means for said releas;n able means comprising a pivotally .mounted latching. membercommon to all the breaker polesV and, having a latching surface thereon, en.- gaging said releasable means, a bimetailic` mem.- ber connected. in series circuit with each pole of the. circuit breaker so as to be heated inresponse to. the fiow therethrough, a magnetic yoke for each of the breaker poles, allprnounted upon the common. latchingv member `each embracing one of the. bimetallic. members so as to ybe magnetically energized in accordance with the current iiowing therethrough, a magnetic armature, pivotally mounted on .each oi' said magnetic yokes, sai-d bimetallic members being connected to rotate the magnetic yokes, arma-'- tures and the common latching member bodily into; unlatching posit-ion4 upon the occurrence. of sustained, moderate current overloads causing iiexing of thel bimetallic members. by the heet developed. therein, said bimetallic members bee ing positioned in the .paths of movement of the armaturesas they are magnetically' .attracted toward their associated yokes soias to' efect ro.- tation of the yokes and common. latching mein-'- ber as an attracted armature rotates. aboutY its point. of engagement with its associated. bi'.- metailic member so.l that theyoke. and. latohing member movement occurs with a substantially pryingv action as` an armature is magnetically attracted to its associated yoke upon tneoccur. rence of heavy` overload or short circuit currents. v f

` JOI-IN. G. JACKSON.

RALPH H. KINGDOM.

No references cited.

Certiicate of Correction Patent No. 2,536,812 January 2, 1951 JOHN G. JACKSON ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 2, after the reference numeral 2 insert formed; line 27, after the Word about insert hubs; column 8, line 26, after flow insert of current;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case 'n the Patent Olce.

Signed and sealed this 20th day of February, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant ommz'ssz'oner of Patents.

Certificate of Correction Patent No. 2,536,812 January 2, 1951 JOHN G. JACKSON ET AL. It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 2, after the reference numeral 2 insert formed, line 27, after the word about insert hubs; column 8, line 26, after flow insert of current; and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case 'in the Patent Oice.

Signed and sealed this k20th day of February, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

